For many years, aircraft have deployed missiles during flight. The missiles have principally been designed to contact a target on the ground, i.e., an air-to-surface missile, or in the air, i.e., an air-to-air missile. In an attempt to control the flight of the missiles, various guidance systems and methods have been developed.
Initially, missiles were unguided and simply dropped from aircraft during flight. The missiles would then free-fall to earth subject to the prevailing gravitational and aerodynamic forces. Thus, following the missile's deployment, the flight pattern of the missile was not controlled. Accordingly, the accuracy with which such missiles contacted the target was relatively low since, even though the crew deploying the missile would generally consider the speed of the aircraft and any known wind conditions in selecting the deployment coordinates for the missile, the missile was subject to numerous unknown sources of error.
The inability to control the flight path of a deployed missile and to correct for errors introduced by unknown sources, such as intermittent high-level wind currents, was unsatisfactory. For example, even a missile which misses its target by only a small distance may either be totally ineffective or may cause inadvertent harm. In either event, however, the missile would have been unnecessarily expended and the target would remain unscathed.
Numerous modern missile applications prefer to launch missiles from remote locations, i.e., locations located many thousands of feet both vertically and horizontally from the intended target, in order to avoid detection or possible retaliation. Missiles capable of such remote deployment are considered to have a long "stand off". The launch of missiles from remote locations further exacerbates the targeting deficiencies of unguided missiles due to the increased duration of the sources of error acting upon the missile during its extended flight from its deployment to the target.
In an attempt to control the flight path of missiles, inertial guidance systems have been placed onboard some missiles. Initialization of such inertial guidance systems is required prior to launch of the missiles. For example, guidance system alignment and target information, such as the coordinates of the launch and target locations is typically downloaded from the launch platform, such as an airplane, via a data interface to the missile prior to launch. Following launch, the onboard guidance system controls the flight path of the missile via the missile's external control surfaces to effectively steer the missile from the launch coordinates to the target coordinates while compensating for external forces.
Such onboard guidance systems typically require the deploying aircraft to be equipped with fire control avionics to download the proper data to the missile prior to its launch. In addition, an appropriate interface between the aircraft avionics and the guidance system of the missile is required. Therefore, the number of properly equipped aircraft and aircraft weapon stations from which such missiles may be launched is limited. In addition, while fire control avionics and an appropriate interface could be added to more aircraft, the cost of the aircraft modifications would be prohibitive.
Another attempt to provide increased accuracy for guided missiles employs sensor systems, such as radar, on the missiles. These missiles are typically referred to as terminal homing missiles. The sensor system of the missile searches for a designated target, and upon recognition of the designated target, controls the flight of the missile such that it impacts upon the target.
Although missiles with inertial guidance and/or terminal homing have improved the accuracy with which targets may be attacked, these missiles typically require expensive electrical and data interfaces with their air or ground launch platforms or complex sensor systems. Thus, it would be desirable to have a missile guidance system that did not require a launch platform to be equipped with an expensive or complex electrical and data missile interface and did not require a complex sensor system.